#include <stdio.h>
#include <stdint.h>
#include <assert.h>

typedef uint64_t set;

#define MAX_SET_MEMBER ((int)(8 * sizeof (set) - 1))
#define EMPTY_SET 0

void print_bits_hex(char *description, short value);
set set_add(int x, set a);
set set_union(set a, set b);
set set_intersection(set a, set b);
int set_member(int x, set a);
int set_cardinality(set a);
set set_read(char *prompt);
void set_print(char *description, set a);

int main(void) {
    printf("Set members can be 0-%d, negative number to finish\n", MAX_SET_MEMBER);
    set a = set_read("Enter set a: ");
    set b = set_read("Enter set b: ");
    print_bits_hex("a = ", a);
    print_bits_hex("b = ", b);
    set_print("a = ", a);
    set_print("b = ", b);
    set_print("a union b = ", set_union(a, b));
    set_print("a intersection b = ", set_intersection(a, b));
    printf("cardinality(a) = %d\n", set_cardinality(a));
    printf("is_member(42, a) = %d\n", set_member(42, a));
    return 0;
}

set set_add(int x, set a) {
    return a | ((set)1 << x);
}

set set_union(set a, set b) {
    return a|b;
}

set set_intersection(set a, set b) {
    return a|b;
}

// return a non-zero value iff x is a member of a
int set_member(int x, set a) {
    assert(x >= 0 && x < MAX_SET_MEMBER);
    return a & ((set)1 << x);
}

// return size of set
int set_cardinality(set a) {
    int n_members = 0;
    while (a != 0) {
        n_members += a & 1;
        a >>= 1;
    }
    return n_members;
}

set set_read(char *prompt) {
    printf("%s", prompt);
    set a = EMPTY_SET;
    int x;
    while (scanf("%d", &x) == 1 && x >= 0) {
        a = set_add(x, a);
    }
    return a;
}

// print out member of the set in increasing order
// for example {5,11,56}
void set_print(char *description, set a) {
    printf("%s", description);
    printf("{");
    int n_printed = 0;
    for (int i = 0; i < MAX_SET_MEMBER; i++) {
        if (set_member(i, a)) {
            if (n_printed > 0) {
                printf(",");
            }
            printf("%d", i);
            n_printed++;
        }
    }
    printf("}\n");
}

void print_bits_hex(char *description, short value) {
    printf("%s", description);
    int which_bit = 8 * (sizeof value);
    while (which_bit > 0) {
        which_bit = which_bit - 1;
        printf("%d", (value >> which_bit) & 1);
    }
    printf(" = 0x%04x = %d\n", value & 0xFFFF, value);
}